Of Shells & Sand

Have you ever walked along a windy beach and noticed shells sitting atop small peaks of sand, like a miniature mountain range? Does a shell “protect” the sand underneath, or does the sand pile up behind it? Does the shell actually cause more erosion around it? How does a shell affect the way sand moves along beaches? What happens when you have millions of shells along a beach? Does that affect the way the beach as a whole erodes? Now what about the parts of a beach that we can’t see, below the water?

Shells emerging from the beach on little pedestals of sand

These might seem like the thoughts of an idle beachgoer, but are actually essential to helping us understand how to sustainably protect our coasts. As part of the TRAILS project, Tjitske Kooistra is investigating how sand nourishments influence sensitive ecosystems on the Dutch coast. In order to do that, we need to understand how shells and sand interact at the bottom of the sea, since there are many locations along the Dutch coast where shells make up a significant portion of the beach material. This is really difficult to understand in the field, so to figure this out in a more controlled setting, Tjitske planned a series of lab experiments and we recruited Steven Haarbosch to carry them out.

After months of hard work shovelling sand and crunching numbers, Steven successfully defended his thesis, “The influence of bivalve shells of different shapes and sizes on current-driven sediment transport“! He conducted excellent, tremendously useful research, and I am really proud of what he accomplished.

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Postdoc Job Opportunity

What is the fate of nourished sand? What are the pathways of sediment on an ebb-tidal delta or in a tidal basin? What role does sediment play in the UNESCO-world heritage area of the Wadden Sea? We are looking for a curious and motivated postdoc to work with us on an exciting project here at TU Delft in the Netherlands.  The main goal of this position is to develop and test novel simulation approaches to trace pathways of different sediment types, and to predict sediment dispersal and morphodynamic responses to different nourishment strategies.

More information about the topic and the application process can be found here: https://www.tudelft.nl/over-tu-delft/werken-bij-tu-delft/vacatures/details/?nPostingId=3875&nPostingTargetId=10801&id=QEZFK026203F3VBQBLO6G68W9&LG=UK&mask=external

I also worked on this project as a postdoc until recently starting a new position, and I really enjoyed both the topic and teammates. Now you have the opportunity to join our team and continue developing this research! A summary of previous work on the project can be found here:
https://coastallycurious.com/2022/12/15/tracking-sand-that-hides-from-the-sun/

Come join our TRAILS team! Feel free to get in touch with us if you have any questions. Applications close March 12th, 2023!

Stuart Pearson (S.G.Pearson@tudelft.nl)
Bram van Prooijen (B.C.vanProoijen@TUDelft.nl)

Tracking Sand that Hides from the Sun

Keeping Dutch feet dry is mainly done by placing piles of sand along the coast as “nourishments”. These nourishments build out the beaches and dunes to act as a protective buffer against storms. However, as was recently pointed out by an official at Rijkswaterstaat, the Dutch water ministry, the Hamvraag or “bacon question” is still “where the heck does all that sand actually go?”

Knowing where nourished sand goes is important for understanding the ecological impact of nourishments, as well as their effectiveness. If you want your sand to reach a certain destination, how much of it actually gets there and how quickly?

Continue reading Tracking Sand that Hides from the Sun